Можно по-разному относиться к Эвансу и его трудам, но байка про Китайскую стену -- однозначно шедевр!

To protect their frontiers from raids by neighboring nomadic warrior tribes, the early Chinese built the Great Wall. It was not an impenetrable barrier, but it allowed a regulated commerce with neighbors while providing an impediment to invasion and other unwanted influence. For two thousand years it defined a boundary that helped the Chinese agricultural civilization to define itself with less disruption from the chaos outside.
Although China might not have become so distinct a culture without the Great Wall, the Wall's construction was immensely expensive and bankrupted at least one dynasty, probably contributing to its fall. The benefits of isolation strategies must be balanced against their costs. There is a time to be pragmatic and make measured revisions to the model, so that it can fit more smoothly with foreign ones.